The present invention relates to a method for fabricating a semiconductor device, and more particularly to a method for verifying optical proximity correction using layer versus layer comparison.
As methods for verifying designs of semiconductor memory devices, such as DRAMs, Design Rule Check (DRC), Layer versus schematic (LVS) comparison, and Layer versus layer (LVL) comparison are used. Particularly, in order to compare an original design of a semiconductor device to a revised design thereof obtained by Optical Proximity Correction (OPC), the LVL comparison is mainly used.
FIG. 1 is a flow chart illustrating a conventional method for verifying optical proximity correction using layer versus layer comparison. FIGS. 2 to 4 are schematic plan views illustrating the method of FIG. 1.
With reference to FIGS. 1 to 4, an original design 200 of a semiconductor device is prepared (step 110). Here, the original design 200 refers to a drawing, on which various patterns 210 for forming unit components of the semiconductor device are disposed. After the original design 200 is prepared, a revised design 300 of the semiconductor device in consideration of an optical proximity effect is obtained by OPC (step 120). Generally, the optical proximity effect means a phenomenon in which as the size of a pattern reaches the limit of resolution, the pattern is damaged by diffraction and interference of light. Accordingly, damaged patterns 310 are disposed in the revised design 300. Thereafter, the original design 200 and the revised design 300 are compared with each other (step 130). By comparing deviation patterns 410 and 420, obtained by results of the above comparison, to reference values, it is determined whether or not the original design 200 contains errors, i.e., whether or not any pattern is omitted from the original design 200, and whether or not the revised design 300 contains errors, i.e., whether or not the revised design 300 is obtained in conformity with a designated rule (step 140).
Since only the sizes of the patterns of the original designs 200 and the revised design 300 are compared with each other, the above conventional method does not take into consideration influence of exposure conditions. For example, according to types of an illuminating system, which is one of the exposure conditions, and particularly according to directions of an off-axis illuminating (OAI) system, different results are obtained. Accordingly, it is difficult to correctly and accurately inspect differences between the original design and the revised design using the method above.